The present invention relates to the field of rolling bearing cages, particularly synthetic cages used in deep-groove ball bearings to provide a suitable circumferential spacing between the balls. The invention also relates to cages for rolling bearings the rings of which are made of thin sheet.
Cages of these types are of annular overall shape with spherical pockets in which the balls are partially housed. The balls are held in the pockets by claws arranged in pairs on the opposite side to the heel of the cage. The spherical pockets have a diameter very slightly greater than that of the balls so that there remains a certain functional clearance between the balls and the pockets. Reference may be made to the abstract of document JP 2002/147 463 (NSK), in which the radial thickness of the claws tapers away from the heel.
When the rolling bearing is running at high speed, centrifugal force subjects the cage to stresses which have a tendency to deform said cage, mainly in the radial direction, and cause it to mushroom, that is to say which give the cage a conical shape by increasing the diameter on the claw side. Deformation such as this has a detrimental effect on the correct operation of the rolling bearing because the edges of the pockets become clamped against the balls, increasing the frictional torque and scraping the lubricant, all this soon leading to accelerated degrading of the lubrication of the bearing. There is also a risk that the ends of the claws will come into contact with the bore of the outer ring of the bearing, with the risk of causing excessive cage wear.